The Parables of Our Lord | Page 3

not as similar but the same. In order that a comparison may be effective either for ornament or for use, there must be, between the two acts or objects, a similarity in some points, and a dissimilarity in others. The comparison for moral or ?sthetic purposes is like an algebraic equation in mathematical science; if the two sides are in all their features the same, or in all their features different, you may manipulate the signs till the sun go down, but you will obtain no useful result: it is only when they are in some of their terms the same and in some different, that you can bring fruit from their union.
We stand here on the brink of a great deep. For wise ends the system of nature has been constructed upon a line intermediate between the extremes of sameness and diversity. If the measure of difference between classes and individuals had been much greater or much smaller than it is, the accumulation of knowledge would have been extremely difficult, or altogether impossible. It is by the combination of similarity and dissimilarity among sensible objects that science from its lowest to its highest measures becomes possible. If all animals, or all plants had been in their sensible qualities precisely the same, there would have been of animals or vegetables only one class: we could have had no knowledge regarding them, except as individuals: our knowledge would at this day have been less than that of savages. Again, if all animals or all plants had been in their sensible qualities wholly dissimilar--all from each, and each from all, it would have been impossible to frame classes; our knowledge, as on the opposite supposition, would have been limited to our observation of individuals. In either case Zoology or Botany would have been impossible. Man, endowed with intelligence, could not, in such a world, have found exercise for his faculties. It would have been like a seeing eye without a shining light. The power would have lain dormant for want of a suitable object. Ask the Botanist, the Naturalist, the Chemist--ask the votary of any science, what makes accumulated knowledge possible; he will tell you, it is the similarity which enables him to classify, accompanied by the diversity which enables him to distinguish. Wanting these two qualities in balanced union there could be no analogy; and wanting analogy, man could not be capable of occupying the place which has been assigned to him in creation.[1]
[1] But in order to employ analogy with effect more is needful than to make sure that the two objects or acts compared are similar without being identical: the design for which a comparison is made enters as an essential element, and decisively determines its value. Between two given objects an analogy may exist, good for one purpose but worthless for another. Given two balls, spherical in form and equal in size, the one of wood and the other of iron; and let the question be, Do these two objects bear any analogy to each other, real in itself and capable of being usefully employed? The question cannot yet be answered: we must first ascertain for what purpose the comparison is instituted. The two balls are like each other in form, but unlike in material; whether is it in respect of their form or their material that you propose to compare them? If one of them rolls along a gently inclined plane, you may safely infer that the other, when placed in the same position, will follow the same course; for although different in other features they are similar in form. But you cannot infer that because one floats when thrown into the water the other will float too, for in respect to specific gravity there is no similarity between them. Again, let two pieces of wood, cut from the same tree, be brought together, the one a cube, the other a sphere; you may safely conclude, if one swim in water that the other will swim too, because though of diverse forms they are of the same specific gravity; but you cannot conclude, if the one roll on an inclined plane, that the other will roll also, because though of the same specific gravity they are diverse forms. Two objects may be compared for the purpose of inferential analogy, although in nine of their qualities they are wholly dissimilar, if they resemble each other in one, and that the quality with respect to which the comparison is instituted. Again, although two objects be similar in nine of their properties, and dissimilar only in one, no useful analogy can be instituted between them if the object for which the comparison is made save with respect to the one point in which they are dissimilar. An acquaintance with such